The present invention is concerned with an automatic control system for regulating lamp brilliance, especially in flasher signals. The system will regulate the brilliance of the light emitted from a variable intensity lamp in reference to ambient light conditions so that the visual effect of the signal is always at a constant optimum level, but the power requirements are reduced during nighttime conditions. The control system is well adapted to flasher signals.
Flasher warning signals comprising a lamp whose circuit is intermittently switched on and off by means of a controlled flasher unit are well known. These devices have become widely used for many purposes. Most typically they are thought of as various signals to be used at night to warn motorists and pedestrians of hazards or obstacles present on highways. Because they are used at night, high intensity light is not necessary to assure the requisite visibility. Moreover, during the day, battery output is conserved by turning the devices off. Indeed, flasher warning signal devices are known which are provided with photocells for turning off the flasher device during the daylight hours. Such daytime off flasher signals are exemplified in U.S. Pat. No. 2,901,669 and U.S. Pat. No. 3,139,556.
Use of flasher signals is not restricted to nighttime hours, however. Flasher signals often are required for daytime use, especially on lighted buoys, or in conjunction with traffic signals and isolated highway signs and the like. It is often desirable, and even sometimes necessary, to operate flasher signals during the daylight hours, such as when they are used in conjunction with highway or building constructions, repair and excavation.
In employing flasher warning signals, or distress signals, during daylight hours, a high intensity flasher is used to assure adequate visability of the signal. Conventional high intensity flashers operate 24 hours a day and put out substantially more light than is necessary for good visability in the evening or nightime hours. Since the power supply to these devices is always limited, the extra power supplied during the dark hours results in higher costs by virtue of the need to expend many man hours of labor in maintaining or replacing the power pack used in such flashers, let alone the cost of the power pack itself.